Omega-3 fatty acids come up a lot in the news. Perhaps you’ve heard that omega-3 supplements can help protect humans against certain chronic illnesses, or that omega-3s may be helpful to decrease symptoms of certain diseases. But what are omega-3s? And should you be taking omega-3 supplements? That’s what we are going to explore in today’s blog post.
Disclaimer: As always, this is general information intended for healthy adults. Your needs may vary based on medical status, lifestyle, or life-stage. Please never replace generalized health information you’ve read online with individualized clinical care.
What are omega-3 and omega-6 fatty acids?
Omega-3 and omega-6 fatty acids are the two major classes of polyunsaturated fatty acids (PUFAs). To read more about dietary fats in general, please see this post.
Omega-3 fatty acids have a carbon-carbon double bond 3 carbs from the methyl end of the chain, hence the name “omega-3s.”
There are many types of omega-3 fatty acids, but there are three main types of omega-3 fatty acids are focused upon when it comes to human health: alpha-linolenic (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
Omega-3s play many important roles in the body. They are one of the major components of cell membranes. They also play a role in providing energy for the body, and are involved in cell signaling, which is important to cardiovascular, immune, and endocrine function. DHA is especially high in the retina, brain, and in sperm.
ALA is an essential fatty acid, meaning your body cannot make it, and thus you must obtain the nutrient from food sources. The human body is able to convert some ALA to EPA (primarily in the liver), and some EPA to DHA, but only in small amounts, with conversion rates typically less than 15%.
Because conversion is so inefficient, it is important to obtain EPA and DHA from the diet to ensure adequate amounts in the body. Which begs the question…
How much omega-3 fatty acids do I need?
Experts have not defined estimated dietary intakes of omega-3 fatty acids. However, adequate intake (AI) values have been proposed by the Institute of Medicine (IOM) for ALA only, because ALA is the only omega-3 that is essential.
The AI values for healthy adult females over 19 years of age is 1.1 grams per day of ALA omega-3s, and 1.6 grams of ALA per day for healthy adult males. It is recommended that pregnant women get at least 1.4 grams ALA per day, and breastfeeding women get at least 1.3 grams per day.
Some researchers have proposed that the ratio of omega-6 to omega-3 fatty acids consumed in the diet is important, and may have implications for the pathogenesis of various chronic diseases, including cancer and cardiovascular disease. However, there has not yet been a consensus of how important the omega-6:omega-3 fatty acid ratio is, and what the optimal ratio would be.
The USDA currently recommends people consume no more than 3 grams of EPA and DHA per day combined.
Research suggests that most people in the US consume the recommended amount of ALA.
What foods contain omega-3 fatty acids?
Some plant oils contain ALAs. Flaxseed (linseed) oil is a rich source of ALAs; soybean and canola oils are other rich sources. Walnuts, hemp hearts, flaxseeds, and chia seeds also contain ALA.
Omega-3s are also found in fatty fish. Salmon, mackerel, tuna, herring, and sardines contain high amounts of long chain omega-3s. Fish that are lower in fat (such as tilapia and cod) contain less omega-3 fatty acids.
Some eggs, yogurts, plant-based yogurts, milks, plant milks (including flax milk), tofus, and juices are fortified with DHA and omega-3 fatty acids. Typically, these are advertised as containing DHA or omega-3s; check your package for further details.
Many people take supplements to get omega-3s. Fish oil and krill oil are popular seafood-based supplements, and algal oil is an increasingly popular vegan alternative.
Here is a quick comparison chart of different foods that are common sources of omega-3s in the human diet:
What about omega-3 supplements like fish oil and algal oil?
As mentioned above, supplements are a common source of omega-3s in the human diet. Omega-3 supplementation came into vogue years ago. Flax oil has also long-existed as a source of omega-3 supplementation. And algal oil capsules have recently increased in popularity as a plant-based alternative to omega-3s.
It’s worth keeping in mind that no supplements are regulated, so it is difficult to know which supplements are best in terms of quality, potency, and purity, which is a real shame because some populations can really benefit from them.
With fish oil supplements in particular, many become concerned about mercury. Some studies have shown fish oil supplements to be less potent than their labels suggest, and others have suggested they may contain heavy metals. While consumption in small amounts is unlikely to cause harm, long-term elevated exposure may lead to heavy metal accumulation and increased health risks.
Algal oil has been shown to increase blood levels of DHA in those who took the supplement, and may be a good alternative to seafood-based supplements for those at risk of deficiency, though some suggest that the bioavailability of these supplements is not yet fully understood, and requires further examination.
I wanted to bring special attention to omega-3 supplements (versus food sources), because much of the research is focused on omega-3 supplements. It’s just something to keep in mind when reading about omega-3s and health claims.
Furthermore, I think it’s important to note that high levels of omega-3 supplement consumption may interact with certain medications, including Warfarin, a commonly prescribed anticoagulant. This is why is an example of why it is essential to discuss dietary supplements with your clinician.
Omega-3 fatty acids and health:
Omega-3 fatty acids have garnered quite a bit of attention in recent years for their potential to support health. That said, a majority of the existing scientific research on omega-3 fatty acids focuses on EPA and DHA from foods like fish, and/or dietary supplements.
Dietary intake studies that have estimated EPA and DHA consumption from reported fish intake have their limitations, because as with all dietary intake literature, studies assessing fish intake are limited by recall bias (ie, survey participants are often unable to accurately recall the food they’ve eaten and in what amounts).
Additionally, it is difficult to ascertain whether or not benefits seen in these studies are due fully attributable to EPA and DHA in seafood, or whether they are somewhat due to reduced consumption of other, less healthful foods (like red meat), or other confounding factors (such as healthier overall diets).
When it comes to omega-3s and cardiovascular disease, despite epi studies that suggested those who consume fish and higher levels of omega-3s had lower risks of cardiovascular disease, clinical studies have repeatedly shown that omega-3 supplementation does not improve risks of cardiovascular events (such as heart attack or stroke), even if they do decrease some biomarkers of cardiovascular health (such as reduced blood triglycerides).
This means that these supplementations may help improve blood lipids, but may not actually protect people from the harmful events of cardiovascular disease, and thus, the current scientific consensus does not support nor refute their use for reducing cardiovascular disease event risk based on existing evidence.
While cardiovascular disease has been a major focus of omega-3 research, omega-3s, particularly DHA are important for fetal growth and brain development.
DHA accumulates in the retina of infants until birth, and in the brain until roughly 2 years of age. Ample maternal DHA intake during pregnancy and breastfeeding supports better infant outcomes, and improved visual motor skills in infants.
When it comes to omega-3 supplementation (specifically, fish oil supplements) in pregnancy, several meta-analyses of fish oil supplementation in pregnancy neither support nor refute their use.
When it comes to food sources of omega-3s such as fish, the FDA recommends pregnant and breastfeeding women consume 8-12 ounces (2-3 servings) of seafood per week from lower-mercury sources, such as salmon, anchovies, mackerel, shrimp, squid, tilapia, and herring.
Pregnant or breastfeeding women who do not eat fish for any reason should be sure to consume other sources of omega-3 fatty acids, such as flax oil, walnuts, chia, etc (see chart above).
When it comes to omega-3s and cancer risk, many scientists hypothesized that increased omega-3 consumption would reduce risks of cancer. However, scientific research has shown there is no consistent relationship between omega-3s and overall cancer risk, with the exception of a possible reduced risk of breast cancer and possibly colon cancer, but more research is needed.
That said, high levels of omega-3 consumption have also been associated with potential increased risk of some cancers, such as prostate cancer, and thus, when it comes to omega-3s and cancer risk, it seems there may be a ‘sweet spot’ of consumption, somewhere between too low and too high, that remains to be precisely parsed out.
When it comes to omega-3s and rheumatoid arthritis, evidence suggests while although omega-3s may not offer substantial benefit as a primary treatment, they may reduce the amount of NSAIDs needed, and/or be helpful in reducing swelling and stiffness, as well as joint pain, when combined with NSAID. However, more research is needed.
Omega-3s are often recommended for patients with depression. However, literature suggests there is insufficient evidence to suggest omega-3 supplementation as a treatment for major depressive disorder. Much of the research existing in this area is of low quality, and (surprise surprise) more research is needed.
Omega-3 deficiency may lead to impaired visual or neurological function, or in the case of mother-infant pairs, underconsumption of DHA/EPA may lead to suboptimal infant growth and development.
Bottom line: What are omega-3s? And should you supplement?
Omega-3 fatty acids are essential fatty acids you must get from foods or supplements in your diet. It is important to get enough of these fatty acids to support healthful brain and visual function, infant development, and cellular membrane structure.
Food sources of omega-3s include flax oil, canola oil, soybean oil, flax seed, chia seed, and some fatty fish, including wild salmon and cod. Fortified milks, yogurts, eggs, plant milks and plant yogurts, and juices may offer additional sources of omega-3s.
There has been much hype about potential health benefits of omega-3 supplements in recent years; however, scientific literature suggests that many of these potential proposed benefits are not strongly supported by evidence. As with most nutrients, those who are at risk for deficiency may benefit from a supplement to meet nutrient needs, but health claims of large doses of omega-3 supplements may have been overstated by mainstream media.
Well, that’s all for now! I hope you enjoyed. If you want to know more about nutrition on a plant-based diet, please see this link.
If you liked ‘What are omega-3s?’ you may also like:
- Nutrition for Vegans: What You Need to Know If You’re on a Plant-Based Diet
- Facts About Dietary Fats
- What You Need To Know About Vitamin B-12, Especially If You’re Vegan